/* isatty() replacement.

   Copyright (C) 2012-2017 Free Software Foundation, Inc.

   This program is free software: you can redistribute it and/or modify

   it under the terms of the GNU General Public License as published by

   the Free Software Foundation; either version 3 of the License, or

   (at your option) any later version.

   This program is distributed in the hope that it will be useful,

   but WITHOUT ANY WARRANTY; without even the implied warranty of

   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License

   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */

#include <config.h>

/* Specification.  */

#include <unistd.h>

/* This replacement is enabled on native Windows.  */

#include <errno.h>

/* Get declarations of the Win32 API functions.  */

#define WIN32_LEAN_AND_MEAN

#include <windows.h>

#if HAVE_MSVC_INVALID_PARAMETER_HANDLER

# include "msvc-inval.h"

#endif

/* Get _get_osfhandle().  */

#if GNULIB_MSVC_NOTHROW

# include "msvc-nothrow.h"

#else

# include <io.h>

#endif

static BOOL IsConsoleHandle (HANDLE h)

{

  DWORD mode;

  return GetConsoleMode (h, &mode) != 0;

}

#if HAVE_MSVC_INVALID_PARAMETER_HANDLER

static int

_isatty_nothrow (int fd)

{

  int result;

  TRY_MSVC_INVAL

    {

      result = _isatty (fd);

    }

  CATCH_MSVC_INVAL

    {

      result = 0;

    }

  DONE_MSVC_INVAL;

  return result;

}

#else

# define _isatty_nothrow _isatty

#endif

/* Determine whether FD refers to a console device.  Return 1 if yes.

   Return 0 and set errno if no. (ptsname_r relies on the errno value.)  */

int

isatty (int fd)

{

  HANDLE h = (HANDLE) _get_osfhandle (fd);

  if (h == INVALID_HANDLE_VALUE)

    {

      errno = EBADF;

      return 0;

    }

  /* _isatty (fd) tests whether GetFileType of the handle is FILE_TYPE_CHAR.

     But it does not set errno when it returns 0.  */

  if (_isatty_nothrow (fd))

    {

      if (IsConsoleHandle (h))

        return 1;

    }

  errno = ENOTTY;

  return 0;

}